public class No_82_2{
	public static void main(String[] args){
		java.util.Scanner sc = new java.util.Scanner(System.in);
		int w,h;
		String s1,s2;
		
		w = sc.nextInt();
		h = sc.nextInt();
		s1 = sc.next();
		if(s1.equals("B")){
			s2 = "W";
		}
		else{
			s2 = "B";
		}
		
		for(int i = 0;i < h;i++){
			for(int j = 0;j < w;j++){
				if((i%2 == 0 && j%2 == 0) || (i%2 == 1 && j%2 == 1)){
					System.out.print(s1);
				}
				else{
					System.out.print(s2);
				}
			}
			System.out.println();
		}
	}
}